Users will complain, that's the steady-state of the universe.
Identify the actual cause of the performance problem and work on fixing that. Then the users might stop complaining for a nanosecond or two. 🙂
This may be worth a read:
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability